The son brings his girlfriend home to meet his father, turning his girlfriend into a stepmother.

Sumire is dating Yosuke with the intention of marrying him. When Yosuke introduced me to my father and came home, he was there with Papa Katsu's former partner. Sumire, who was suggested by her father to live with the three of them, accepted this because she was worried that her father's activities would be disrupted if she was in a bad mood. One day, when they started living together, Yosuke suddenly had something to do, and his father, who was alone with Sumire, slipped him a type of aphrodisiac in his drink.